T Cells Show Differences Between Psoriasis and Atopic Dermatitis

Psoriasis is a systemic disease, while atopic dermatitis (AD) is a skin-focused, allergen-driven disease, according to results from T-cell receptor sequencing performed in a recent study published in Allergy.

Researchers aimed to determine the extent to which infiltrating T cells into the skin of patents with AD and psoriasis are antigen-specific skin-homing T cells or unspecific heterogeneous bystander cells. Investigators obtained T cells from lesional skin and blood of 9 patients with AD and 10 patients with psoriasis and compared them by receptor (TCR) sequencing. The blood cells were sorted according to expression of the cutaneous leukocyte antigen (CLA) into skin-homing (CLA+) and non-skin-homing (CLA-) fractions.

Comparisons determined that clonally expanded T cells in skin lesions of patients with AD and psoriasis corresponded to skin-homing circulating T cells. These T-cell clones were more detectable among CLA- circulating T cells in patients with psoriasis. Overlapping TCR sequences identified allergen-specific infiltrating cells in up to 28% of infiltrating cells in AD skin.

“Our data show that in line with the systemic nature of psoriasis, T-cell clones that infiltrate psoriatic skin lesions do not exclusively possess skin-homing ability and are therefore most probably specific to antigens that are not exclusively expressed or located in the skin,” concluded the study authors. “T cells driving AD skin inflammation appear to home nearly exclusively to the skin and are, to a certain extent, specific to aeroallergens,” they added.

Reference
Roesner LM, Farag AK, Pospich R, Traidl S, Werfel T. T-cell receptor sequencing specifies psoriasis as a systemic and atopic dermatitis as a skin-focused, allergen-driven disease. Allergy. 2022;10.1111/all.15272. doi:10.1111/all.15272